The affordability and accessibility of electronic keyboards make them a popular alternative to traditional, acoustic keyboard instruments, such as full-size pianos. Electronic keyboards can cover most, if not all, of the popular acoustic and electronic instrument sounds. The main difference between electronic keyboards and acoustic keyboards is that the sound created does not come from the physical movement of a string. In an acoustic piano, pressing a key causes a hammer to drop down and strike one or more strings, and the string vibration sets the surrounding air into motion, creating sound waves. The sound from an electronic keyboard comes from continuously changing electrical signals (analog) or a stream of numbers generated by a microprocessor (digital). The electrical signal of analog instruments is heard through loud speakers which convert the changes in electrical polarity to air movement, resulting in sound. Digital instruments work similarly, but the stream of numbers must first be converted into a continuous electrical signal by an internal component referred to as a digital-to-analog converter (DAC).
Electronic keyboards are also much smaller and lighter, making them ideal for portable use. They can also be connected to a computer and integrated with software to compose, record, and playback music. FIG. 1 illustrates a top view of a conventional electronic keyboard that includes a frame that surrounds a number of black and white keys. The keyboard is also equipped with various knobs, buttons, rockers switches, and other types of controllers to manipulate modulation, pitch bend, and octave. These controller buttons are typically positioned on the frame around the keys for easy access by the user.
To enhance portability, current electronic keyboards have fewer keys relative to the full 88 keys of conventional pianos. However, electronic keyboards are limited to how small they can be, because keys have standard sizes comparable to piano keys, and a shorter keyboard limits what can be played. The number of keys on a conventional portable keyboard can vary, but typically have enough keys to provide a range between 2 to 5 octaves. As the number of keys on an electronic keyboard increases, the portability of the keyboard decreases because of size and weight considerations. U.S. Pat. No. 6,259,006 to Parienti (“the '006 patent”) describes a portable foldable electronic piano made of multiple sections that are evenly sized, and joined together by a flexible membrane. When folded, the sections stack on top of each other with a length and width of one section. One disadvantage of the '006 patent keyboard is that the overall size of the keyboard and the number of keys available to a user, when unfolded, is pre-set. In order for the '006 patent keyboard to be operational, all the keyboard sections must be unfolded. Because the keyboard sections are physically attached together when folded or unfolded, there is no option to remove or add keyboard sections. This limits the type of music can be played with the keyboard, based on the number of keys and octaves available.